So far as I am aware of, there is no clearly visible objective and verifiable evidence that God exists.
All the evidence is subjective in nature, personal accounts of Gods intervention, conversations, and so forth.
An aetheist would have to know more than I do, for an aetheist knows there is no God
– Carl Sagan
What Carl Sagan is referring to, is the lack of evidence to disprove Gods existance, hence it is rational to conclude that Carl Sagan is an agnostic.
Some people are “functional aetheists”, remaining uncertain as to whether God exists or not, but seeing no signs of God anywhere around us.
I think whether you believe or not, has to do with your own experiences – it is easier to believe in something if you have seen it for youreslf, and whether you believe other people who state they have experienced contact by God.